Liquid crystal displays of the prior art commonly employ spaced conductive lattice networks, single conductive planes with spaced conductive lattice networks, or pairs of conductive planes. Such arrangements have liquid crystal material between conductive networks and/or planes to apply the fields which create reorientation and the resulting images in the liquid crystal material.
A great variety of liquid crystal devices have been developed, even some which could be described as slates or the like, and some are shown to be addressed or imaged using a stylus-like device. Some devices of the prior art include those disclosed in U.S. Pat. No. 4,814,760 (Johnston et al.), U.S. Pat. No. 3,781,085 (Liebowitz), U.S. Pat. No. 4,685,770 (Baeger), U.S. Pat. No. 4,525,032 (Hilsum), U.S. Pat. No. 3,947,183 (Haas et al.), U.S. Pat. No. 4,723,836 (Kono et al.), U.S. Pat. No. 4,527,862 (Arakawa) and U.S. Pat. No. 3,886,311 (Rodgers et al.).
The typical construction of such display devices may be said to represent a "sandwich" with liquid crystal material between two layers of conductive material. Such devices are typically incapable of providing an image except at the locales sandwiched between conductive material.
Such typical sandwich construction of liquid crystal devices has disadvantages which have limited the usefulness of liquid crystal technology in certain applications such as drawing/writing slates or the like, particularly simple stand-alone devices. One disadvantage is that such devices do not readily lend themselves for use in free-form writing or drawing. In some devices of the prior art, it is not possible to obtain a solid continuous line. Some devices, because of how they function, unnecessarily limit the creative skills of the user; because they are point-, line-, or area-limited, they do not lend themselves to creation of artistic images, for example, of the type possible with devices such as brushes, pads, or even fingers of the hand. When used for writing or drawing, the writer/artist needs a device on which an image can be formed at any desired area, not just at limited areas.
The devices of the prior art fail to appreciate the variety of ways in which an electrical potential used for imaging can be extended to the image-displaying surface area.
Liquid crystal devices of the prior art tend to be fairly complex and expensive in construction. They do not readily lend themselves to wide usage for writing/drawing usage, classroom usage, toy or game uses, or the like. In addition, certain prior devices do not have simple, easily usable erasing means.
A variety of light-modulating liquid crystal products have been made utilizing LC-layers which have a polymeric material forming and holding micro-volumes of liquid crystal material. However, LC-layers of this type have heretofore not been successfully utilized in simple slate products of the writing/drawing type.
A simplified liquid crystal display device overcoming some of problems and shortcomings of the prior art would be an important advance in the art.